1. Field of the Invention
The invention relates generally to the field of integrated circuit (IC) device packaging technology and, more particularly to heat sink attachment in IC device packages.
2. Background Art
IC semiconductor dies are typically mounted in or on a package that is attached to a printed circuit board (PCB). Example IC device packages include ball grid array (BGA), pin grid array (PGA), and land grid array (LGA) packages. A conventional BGA package has an array of solder balls located on a bottom external surface of a package substrate. The solder balls are reflowed to attach the package to the PCB. The IC die is typically mounted to a top surface of the package substrate. Wire bonds typically couple signals of the IC die to the substrate. The substrate has internal routing that electrically couples the signals of the IC die to the solder balls on the bottom substrate surface. A molding compound encapsulates the IC die, wire bonds, and the entire or partial top surface of the substrate to provide environmental protection.
Die-up and die-down BGA package configurations exist. In die-up BGA packages, the IC die is mounted on the top surface of the substrate, so that the active surface of the IC die is directed away from the PCB. In die-down BGA packages, the IC die is mounted on the bottom surface of the substrate, so that the active surface of the IC die is directed towards the PCB.
Problems with conventional IC packages include poor thermal performance. IC dies can generate a large amount of heat during operation in an IC package. Heat sinks are frequently attached to IC packages to aid in removing the heat from the IC package. However, presently used heat sinks do not make efficient contact with the IC package due to limitations of conventional adhesives, and thus any increase in thermal performance due to heat sinks is still limited.
What is needed is enhanced attachment mechanisms for heat sinks to IC packages, such as BGA packages, that provide enhanced ability to dissipate heat generated by the IC die.